Scapula alata in early breast cancer patients enrolled in a randomized clinical trial of post-surgery short-course image-guided radiotherapy.

Background: Scapula alata (SA) is a known complication of breast surgery associated with palsy of the serratus anterior, but it is seldom mentioned. We evaluated the risk factors associated with SA and the relationship of SA with ipsilateral shoulder/arm morbidity in a series of patients enrolled in a trial of post-surgery radiotherapy (RT).

Methods: The trial randomized women with completely resected stage I-II breast cancer to short-course image-guided RT, versus conventional RT. SA, arm volume and shoulder-arm mobility were measured prior to RT and at one to three months post-RT. Shoulder/arm morbidities were computed as a post-RT percentage change relative to pre-RT measurements.

Results: Of 119 evaluable patients, 13 (= 10.9%) had pre-RT SA. Age younger than 50 years old, a body mass index less than 25 kg/m2, and axillary lymph node dissection were significant risk factors, with odds ratios of 4.8 (P = 0.009), 6.1 (P = 0.016), and 6.1 (P = 0.005), respectively. Randomization group was not significant. At one to three months' post-RT, mean arm volume increased by 4.1% (P = 0.036) and abduction decreased by 8.6% (P = 0.046) among SA patients, but not among non-SA patients. SA resolved in eight, persisted in five, and appeared in one patient.

Conclusion: The relationship of SA with lower body mass index suggests that SA might have been underestimated in overweight patients. Despite apparent resolution of SA in most patients, pre-RT SA portended an increased risk of shoulder/arm morbidity. We argue that SA warrants further investigation. Incidentally, the observation of SA occurring after RT in one patient represents the second case of post-RT SA reported in the literature.